1. Field of the Invention
The present invention relates to a ratchet wrench, and particularly to a head-tiltable-type ratchet wrench whose head can be tilted relative to a handle.
2. Background of the Invention
Japanese Patent Application Laid-Open (kokai) No. 10-217140 discloses a conventional ratchet wrench having a rotatable head.
In the disclosed ratchet wrench, upon operation of a lever, pressurized air is fed to a motor, so that the motor operates. The motor rotates a drive member, which in turn rotates a first bevel gear. The first bevel gear rotates a third bevel gear via a second bevel gear. The third bevel gear rotates a drive shaft to which a socket is fixed, so that the socket rotates to tighten or loosen a threaded fastening element. Upon release of the lever, the feed of the air to the motor is stopped and the drive shaft stops its rotation. When the position of the head is changed relative to the handle, a pin is moved to a release position, and the head is pivoted to a selected position. As described above, the conventional ratchet wrench includes a plurality of bevel gears provided between the head and the handle so as to enable pivoting of the head in a plane containing the axis of the handle.
Need for a ratchet wrench which can tighten or loosen a threaded fastening element at a difficult-to-access location has become stronger, as has need for a ratchet wrench which permits an operator to insert the ratchet wrench into a narrower space than in the case of the conventional ratchet wrench currently in use.
In order to insert a ratchet wrench into a narrower space, the head, which is a rotatable or tiltable portion, of a ratchet wrench is desired to be as short as possible. Since the conventional ratchet wrench disclosed in the abovedescribed patent publication has the bevel gears between the head and the handle, the head cannot be shortened.
In consideration of the above-described problem of the conventional ratchet wrench, an object of the present invention is to provide a ratchet wrench whose head can be made shorter in order to enable insertion into narrower spaces.
The present invention provides a ratchet wrench comprising: a handle within which a motor Is accommodated; a head provided with a ratchet mechanism having a rotary tightening member which is to be rotated by drive power from the motor; a pin extending in a transverse direction with respect to the axis of the handle so as to connect the head with the handle; a crankshaft connected to an output shaft of the motor; a first drive bush into which a crankpin of the crankshaft is rotatably fitted; a first drive member into which the first drive bush is fitted to be slidable in a direction substantially perpendicular to the axis of the pin, the first drive member being connected to the pin in such a manner that the first drive member is rotatable about the pin and slidable along the pin; a second drive member connected to the pin in such a manner that the second drive member is rotatable about the pin and slidable together with the first drive member along the pin; a second drive bush into which the second drive member is fitted so as to be slidable in a direction parallel to the axis of the head; and a yoke which is connected to the second drive bush in such a manner that the yoke is swingable relative to the second drive bush, the yoke being connected to the rotary tightening member via the ratchet mechanism.
The ratchet wrench of the present invention enables a worker to tighten or loosen a bolt, nut, or other fastening element in a state in which the head is directed to a desired angular direction.
Preferably, the ratchet wrench of the present invention further includes a tilt mechanism which locks the head at an angle selected from a plurality of angles relative to the axis of the handle. The head is securely locked to the handle, so that a bolt or nut within a small space is tightened or loosened securely and easily.
Preferably, the tilt mechanism includes an engagement member having a toothed portion, the engagement member being fixed to the head and rotatably connected to the pin; and a lock pin which is disposed in a front portion of the handle and is engaged with the engage member so as to lock the head. This structure enables a worker to direct the head to a desired angular direction through a simple operation of holding the handle in one hand and the head in the other hand and bending the ratchet wrench about the axis of the pin.
Preferably, the crankshaft is connected to the motor via a reduction gear mechanism.